The Flow Cytometry Core's goal is to optimize Program Project scientific productivity by providing access to state-of-the-art equipment, novel reagents, and specialized expertise in all aspects of flow cytometry. Both Projects and the Tetramer Core rely heavily on flow cytometry techniques. Program Project support allows the Flow Core to contract with the UMMS Flow Cytometry Facility to provide Project Investigators with preferential access to unique services (including cell sorting and complex flow cytometry analytical experiments) and specialized facilities that are not available in individual Investigators' laboratories at reduced rates. The Flow Cytometry Core also works actively with Program Project investigators to develop state-of-the-art protocols and experimental approaches and works with the Tetramer Core in the generation and validation of new reagents. Finally, the Flow Core provides training and workshops to Project and Core investigators and our trainees (post-doctoral fellows and graduate students). RELEVANCE (See instructions): A key goal of this Program Project is to use the EBV model of persistent infection to characterize the development and evolution of virus-specific and cross-reactive CD8+ T cells. These studies will improve our understanding of the development of Cd8+ T cell responses and will allow us to better understand how EBV- specific and cross-reactive CD8+ T cells contribute to either control of viral replication or immune pathology. The Flow Cytometry Core provides access to state-of-the-art equipment, novel reagents, and specialized flow cytometry expertise to all Project Investigators and the Tetramer Core.